import "golang.org/x/image/riff"
Package riff implements the Resource Interchange File Format, used by media formats such as AVI, WAVE and WEBP.
A RIFF stream contains a sequence of chunks. Each chunk consists of an 8-byte header (containing a 4-byte chunk type and a 4-byte chunk length), the chunk data (presented as an io.Reader), and some padding bytes.
A detailed description of the format is at http://www.tactilemedia.com/info/MCI_Control_Info.html
LIST is the "LIST" FourCC.
FourCC is a four character code.
func NewListReader(chunkLen uint32, chunkData io.Reader) (listType FourCC, data *Reader, err error)
NewListReader returns a LIST chunk's list type, such as "movi" or "wavl", and its chunks as a *Reader.
NewReader returns the RIFF stream's form type, such as "AVI " or "WAVE", and its chunks as a *Reader.
type Reader struct {
// contains filtered or unexported fields
}Reader reads chunks from an underlying io.Reader.
Code:
package main
import (
"fmt"
"io"
"io/ioutil"
"log"
"strings"
"golang.org/x/image/riff"
)
func main() {
formType, r, err := riff.NewReader(strings.NewReader(data))
if err != nil {
log.Fatal(err)
}
fmt.Printf("RIFF(%s)\n", formType)
if err := dump(r, ".\t"); err != nil {
log.Fatal(err)
}
}
func dump(r *riff.Reader, indent string) error {
for {
chunkID, chunkLen, chunkData, err := r.Next()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
if chunkID == riff.LIST {
listType, list, err := riff.NewListReader(chunkLen, chunkData)
if err != nil {
return err
}
fmt.Printf("%sLIST(%s)\n", indent, listType)
if err := dump(list, indent+".\t"); err != nil {
return err
}
continue
}
b, err := ioutil.ReadAll(chunkData)
if err != nil {
return err
}
fmt.Printf("%s%s %q\n", indent, chunkID, b)
}
}
func encodeU32(u uint32) string {
return string([]byte{
byte(u >> 0),
byte(u >> 8),
byte(u >> 16),
byte(u >> 24),
})
}
func encode(chunkID, contents string) string {
n := len(contents)
if n&1 == 1 {
contents += "\x00"
}
return chunkID + encodeU32(uint32(n)) + contents
}
func encodeMulti(typ0, typ1 string, chunks ...string) string {
n := 4
for _, c := range chunks {
n += len(c)
}
s := typ0 + encodeU32(uint32(n)) + typ1
for _, c := range chunks {
s += c
}
return s
}
var (
d0 = encode("ZERO", "")
d1 = encode("ONE ", "a")
d2 = encode("TWO ", "bc")
d3 = encode("THRE", "def")
d4 = encode("FOUR", "ghij")
d5 = encode("FIVE", "klmno")
d6 = encode("SIX ", "pqrstu")
l0 = encodeMulti("LIST", "GOOD", d1, d5)
l1 = encodeMulti("LIST", "BAD ", d3)
l2 = encodeMulti("LIST", "UGLY", d4, d6)
l01 = encodeMulti("LIST", "META", l0, d0, l1)
data = encodeMulti("RIFF", "ROOT", d0, d1, l01, d2, l2)
)
Next returns the next chunk's ID, length and data. It returns io.EOF if there are no more chunks. The io.Reader returned becomes stale after the next Next call, and should no longer be used.
It is valid to call Next even if all of the previous chunk's data has not been read.
Package riff imports 4 packages (graph) and is imported by 2 packages. Updated 6 days ago. Refresh now. Tools for package owners.